Absorbent article having separately attached side-flaps, and a method of manufacturing such an article

ABSTRACT

An absorbent article, particularly a diaper, has a central absorbent unit (1) which is comprised of an elongated absorbent body (2) enclosed between a liquid-permeable inner casing sheet (3) which lies proximal to the wearer in use, and a liquid-impermeable, outer casing sheet (4) which lies distal from the wearer in use. The absorbent unit is provided along its longitudinal edges (9) with liquid-impermeable folds (6) which are upstanding from the inner casing sheet and which form side-leakage barriers. The article has a side-flap (18) on each side of the absorbent unit (1). The side-flaps (18), optionally with associated edge (21, 23), are produced in the form of rectangular strips (10) completely separated from the absorbent unit (1) and are thereafter jointed thereto. A longitudinally extending edge-part (13) of each strip (10) is suitably folded double and the backwardly fold part (19) is joined to the outer casing sheet (3a, 4b or 4) of the absorbent unit (1)along a curved fastening line (21). When the aper is to be used, the side-flaps (18) are pulled-out laterally, the length of this extension, and therewith the width of the resulting side-flaps (18), being dependent on the curved shape of the fastening line (21). It is therewith possible to produce a curved contour (16) of the diaper for conforming to the wearer&#39;s legs with side-flaps (18) which originally have straight edges (11) The material from which the side-flaps (18) are made can be chosen quite independently of the inner and the outer casing sheets (3, 4), so as to avoid irritation of the wearer&#39;s skin while still fitting closely to the wearer&#39;s legs.

FIELD OF THE INVENTION

The present invention relates to absorbent articles, such as diapers,incontinence guards, sanitary napkins and like articles, and inparticular to an absorbent disposable article.

DISCUSSION OF RELATED ART

The curved outer contour desirable to adapt the side-flaps to thewearer's legs so as to hold the absorbent unit correctly positioned,creates difficulties in manufacture. When the casing-layer startingmaterial is in the form of a web of uniform width, the contour can beproduced by clipping away edge-parts. The drawback with this method isthe wastage that occurs, this wastage increasing the costs of materialand requiring separate handling of the waste to remove it from theclipping station during manufacture. Another problem is encountered whenthe article is to be provided with edge elastic along its outer contourduring the manufacture of the elastic article, since it is difficult toapply elastic elements along a curved line when said elements concernedhave the form of relatively broad bands which are to be fastened to oneor both surfaces of the side-flaps or between layers included therein.

In order to avoid these problems, it is proposed, for instance, inEP-A2-0,145,080, to form an upstanding fold of a centre part of eachlong side of a rectangular diaper blank. The folds are folded-in overthe absorbent body and glued to the inner casing sheet. In this way, thecentre part of the diaper, the crotch part, is given a narrower shapewithout needing to clip-out the contour. Edge elastic can be appliedalong the straight edges prior to forming the folds. However, thisdiaper has the drawback that the effective width of the absorbent bodyis reduced by the overlying folds, in which the liquid-impermeable outercasing sheet is included. The folds may also cause the diaper to be feeluncomfortable when the diaper is worn.

OBJECT AND SUMMARY

The present invention is intended to avoid the aforesaid problems and toprovide an absorbent article which has a curved outer contour when inits position of use and which can be manufactured readily without wasteand can be readily provided with broad edge elastic when so desiredwhile, at the same time, avoiding a reduction in the active width of theabsorbent body when forming the curved outer contour.

In the case of known diapers that are provided with side-flaps, thesheet material from either the inner or the outer casing sheet of thediaper, or from both sheets, is included in the side-flaps. This causeslimitations with regard to the choice of a material that will ensurethat the side-flaps do not irritate the wearer's skin and, at the sametime, possess the elastic properties desired. Accordingly, a furtherobject of the invention is that the material from which the side-flapsare made can be chosen quite independently of the materials used in theinner and the outer casing sheets.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which

FIG. 1 is a perspective, sectional view taken on the line I--I in FIG. 2and shows part of a disposable diaper according to a first embodiment ofthe invention, said diaper being shown laterally extended;

FIG. 2 illustrates that side of the diaper in FIG. 1 which lies remotefrom the wearer in use, said diaper being shown outstretched in itslongitudinal direction to a flat state, and the left and the righthalves of the Figure showing the diaper before and after being extendedlaterally; and

FIGS. 3 and 4 illustrate a second embodiment of the invention in amanner similar to FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Figures illustrate a disposable diaper, which has a so-calledhourglass shape in its use state. The diaper includes an absorbent unit1 which comprises an absorbent body 2 which is enclosed between an innerand an outer casing sheet 3 and 4 respectively. The casing sheet 3 ismade of a liquid-permeable and soft sheet material, for instance anonwoven material, and is intended to lie proximal to the wearer in use.The outer casing sheet 4 is made of a liquid-impermeable material, suchas plastic sheet for instance. The absorbent body 2 may, for instance,include absorbent fibre material, such as cellulose fluff, to whichso-called superabsorbent material has been added. The absorbent body 2is elongated and has two mutually opposing and mutually parallellongitudinally extending side-edges 5, of which only one is seen inFIGS. 1 and 3 respectively, these Figures essentially showingone-quarter of the diaper.

In the case of the preferred embodiment illustrated in FIGS. 1 and 2,the outer casing sheet 4 is folded-up at the side-edges 5 of theabsorbent body 2 and an edge-part 4a of said sheet 4 rises up over thesurface of the absorbent body 2 at each edge 5. The inner casing sheet 3is formed with a fold 6 at each of the side-edges 5 of the absorbentbody, this fold embracing the upstanding edge-part 4a of the outercasing sheet 4. The inner casing sheet 3 forms above the edge-part 4a asleeve 7 which extends in the longitudinal direction of the absorbentunit 1 and in which a pre-stretched elastic element 8, for instance arubber thread, extends. The folds 6 form standing barriers which preventfluid leaking laterally from the absorbent unit.

As shown in FIG. 1, the material in the inner casing sheet 3 extendsfrom the sleeve 6 down along the outside of the edge-part 4a and alongitudinally extending edge-part 3a of said sheet 3 is folded-inbeneath the absorbent body 2, outside the casing sheet 4.Correspondingly, an edge-part 3b of the casing sheet 3 is folded-inbeneath the casing sheet 4 from the other edge (not shown in FIG. 1) ofthe absorbent unit 1. The edge-parts 3a, 3b overlap and are joinedtogether on the underside of the absorbent unit 1. The edge-pans therebyform outside the outer casing sheet 4 a further outer or external casingsheet which comprises the same material as the inner casing sheet 3,whereby the diaper obtains an improved, unitary appearance and itsoutside is more pleasant to the touch. However, it is not necessary forthe inner casing sheet 3 to extend down along the full outer side of thefold 6, and the fold configuration illustrated in FIG. 3, in which theouter casing sheet 4 is exposed on the outer surface of the diaper, canbe used alternatively in the inventive diaper embodiment illustrated inFIGS. 1 and 2.

The fold lines between the lower part of the fold 6 and the edge-parts3a, 3b, or the outer casing sheet 4 when no edge-pans 3a, 3b arepresent, are straight and parallel and form long sides 9 of theabsorbent unit 1, which in the preferred embodiment has a rectangularshape.

An elongated strip 10 of skin-friendly sheet material, for instance abreathable, vapour-permeable fibre material, so-called nonwovenmaterial, having straight, parallel side-edges 11, 12 is placed adjacenteach of the long sides 9 of the absorbent unit 1. A first part 13 of thewidth of the strip 10 is located on the outside of the external casingsheet 3a, 3b. The other, remaining part 14 of the width of the strip 10is located laterally outside the side-edge 9 of the absorbent unit 1.Edge elastic or leg elastic is mounted along the outer edge 11 of thestrip 10 in the form of a band 15, preferably elastic material such asrubber, plastic foam, elastic nonwoven material or the like. The band 15is folded around the side-edge 11 and is fastened to both surfaces ofthe strip 10 adjacent the edge 11, for instance glued thereto. The band15 may form outside the side-edge 11 a sleeve-like fold 16 in which anelongated elastic element 17 can be mounted in a pre-stretched state.The outer part 14 of the strip 10 and the band 15 together form a diaperside-flap 18 which is located outside the absorbent unit 1.

That part 19 of the first strip part 13 that lies nearest the innerside-edge 12 of the strip 10 is folded back through 180° about a foldline 20 which, in the idle or rest state of the diaper, extends parallelwith the side-edge 12 of the strip 10. This is shown in the left-handpart of FIG. 2. The backwardly-folded part 19 is positioned between theremainder of the strip-part 13 and the external casing sheet 3a, 3b andis joined thereto, for instance glued or welded thereto, along afastening line 21 spaced from the side-edge 12. As will be seen from theleft side of FIG. 2, the fastening line 21 is curved such that itsdistance d from the fold line 20 is smallest at the transverse centreline of the diaper and greatest at the front and rear waist edges 22 and23 of the diaper.

The diaper is provided with self-gripping tapes or burr fasteners, 24,25 on its rear waist-edge 23. When the diaper is to be put on, theself-gripping tapes 24, 25 are gripped on both sides of the absorbentunit 1 and pulled apart and then passed around the wearer's waist andfastened across the wearer's stomach, so as to form a waistband 24, 25.The front end-edge of the diaper is moved up over the stomach and thefront corners of the diaper are gripped and pulled apart. The corners,i.e. the ends of the side-flaps 18, adjacent the front waist-edge 22 areprovided with self-gripping strips 26, 27 which are complementary to thetapes 24, 25, such as to enable the strips to be fastened to the tapes.The waist-band and the self-gripping tapes may be of an earlier knownkind and are consequently not shown or described in detail in thisdocument.

As the side-flaps 18 are pulled apart laterally in the aforesaid manner,when putting on the diaper, the inner part 13 of the strip 10 and thefold line 20 move laterally outwards towards the side-edge 9 of theabsorbent unit 1. The movement of each point along the fold line 20 isarrested when said point reaches the fastening line 21. Since the innerpart 13 of the strip 10 is folded double, the maximum distance D movedby each point along the fold line 20, and therewith each point along theouter-edge 16 of the side-flaps 18, is equal to twice the aforesaiddistance d between the fastening line 21 and the fold line 20 at saidpoint. To illustrate this, that edge of the band 15 which is located onthe outside of the outer part 14 of the strip 10 is referenced 28.Indicated with a chain line 29 in the right-hand part of FIG. 2 is theposition of said edge 28 when the diaper is extended longitudinally butnot laterally, corresponding to the full straight line 28 shown in theleft-hand part of FIG. 2. The aforesaid maximum movement path D iscorresponded by the distance between the lines 28 and 29, wherein D=2dfor each line transversely across the diaper.

The absorbent unit 1 of the exemplifying embodiment illustrated in FIGS.3 and 4 is also provided with leakage barriers formed by folds 6 havingan elastic element 8 mounted in an upper sleeve 7. In the case of theFIG. 3 embodiment, however, the inner casing sheet 3 is not drawn downalong the full height of the fold 6 on the outside of the upstandingedge-part 4a of the outer casing sheet 4 as in the case of the FIG. 1embodiment, but terminates with a narrow edge-part 3c which extends downfrom the sleeve 7 through only a part of the height of the fold 6 and isjoined, for instance glued, to the outside of the edge-part 4a.

In the case of the embodiment illustrated in FIGS. 3 and 4, the strips30 are made of an elastic or plastically deformable material and intheir rest state have parallel edges 31, 32. A first part 33 of thewidth of each strip 30 extends over the outside of the outer casingsheet 4 and is fastened thereto by means of a glue bead or a weld join34, which extends in a straight line parallel with the edge 32 of thestrip. The other parts 35 of the strips 30 located outside the longsides 9 of the absorbent unit 1 form the diaper side-flaps 36, which inthis case are totally formable.

Because the side-flaps 36 are made of an elastic or formable material,the side-flaps will lie conformingly against the wearer's legs whenextended, and therewith hold the absorbent unit 1 in the desiredposition. However, the side-flaps 36 may also be provided with further,separate edge elastic when so desired, for instance an elastic threadalong the outer edge 31 of the strip 30.

When manufacturing diapers or absorbent articles in accordance with theinvention, the absorbent unit 1 is first produced separately per se andthe strips 10 or 30 forming the respective side-flaps 18, 36 are alsoproduced separately per se. When the side-flaps are to have separateedge-elastics 15-17, these elastics are mounted at this stage of themanufacturing process. The first, inner parts 13, 33 of respectivestrips 18, 36 are then joined, glued or welded, to the outer casingsheet 4 of the absorbent body 1, either along a curved fastening lineaccording to FIGS. 1 and 2, or along a straight fastening line accordingto FIGS. 3 and 4.

When manufacturing absorbent articles according to FIGS. 1 and 2, anabsorbent unit is produced by enclosing absorbent material between amoving web of liquid-permeable sheet material 3 and a moving web ofliquid-impermeable sheet material 4. The folds 6 which form thelongitudinally extending side-leakage barriers are formed at the sametime in this stage of manufacture, if so desired.

Separate from the manufacture of the absorbent unit 1, there are formedfrom sheet material two moving side-flap webs 10 which are provided withedge elastic 15, 17. The two side-flap webs and the absorbent-unit webare then brought together. A first part 13 of the width of the weblocated adjacent the side-edge of each side-flap web 10 is folded doublearound a straight longitudinally extending fold line 20, see theleft-hand part of FIG. 2. The backwardly-folded part 19 is joined to theouter or external casing sheet 3a, 3b or 4 of the absorbent-unit web 1along a longitudinally extending fastening line 21, wherein the distanceof the fastening line 21 from the longitudinally extending side-edge 9of the absorbent-unit web 1 is varied during manufacture, so that thefastening line 21 becomes curved. That part of the side-flap web-part 13which is not folded back extends from the fold line 20 towards andbeyond the longitudinally extending side-edge 9 of the absorbent-unitweb 1 and there merges with a second, remaining width-part 14 of theside-flap web 10, which thus lies laterally outside said side-edge 9.

Separate absorbent articles are cut from the thus produced, movingarticle web, by cutting the web transversely.

I claim:
 1. An absorbent article having an elongated absorbent unit,comprising:a liquid-permeable first, inner casing sheet which forms partof a side of the article which lies proximal to the wearer in a wornstate of the article; a liquid-impermeable second, outer casing sheet;and an elongated absorbent body enclosed between said first and secondcasing sheets; the absorbent unit having two opposing long sides; theabsorbent article further having along each of said long sides aside-flap which is made of a strip of soft sheet material whose lengthis greater than its width, and which is separate from but joined to oneof said casing sheets and an outer contour of the side flap facing awayfrom the absorbent unit is curved in the worn state of the article; eachof said strips has a longitudinally extending first part forming aportion of the width of the strip located adjacent the absorbent unit,and a longitudinally extending second part forming a remaining width ofthe strip located laterally outside the long side of the absorbent unit;the first strip part extends in across the adjacent long side of theabsorbent unit and is joined to the absorbent unit; the second strippart is extendible in a transverse direction of the strip from a firststate assumed when the article is unused to a second state assumed whenthe article is worn; and wherein in said first state the outer contourof said second strip part, and thus the side flap, is a substantiallystraight line, whereas in said second state the transverse extension ofthe second strip part varies along a length of the strip so that thestrip obtains said curved outer contour along at least a center portionof the article.
 2. The article according to claim 1, wherein theabsorbent unit is essentially rectangular and has parallel long sides.3. The article according to claim 1, wherein adjacent to and along eachof the long sides of the absorbent unit, there is formed in the innercasing sheet an upstanding fold which encloses at least partially asimilar upstanding edge-part of the outer casing sheet; andan elongatedelastic element is mounted in the fold in a prestretched state outsidesaid upstanding edge-part.
 4. The article according to claim 1, whereinsaid first part of the strip presents a part which is folded backthrough 180° so as to be located between a remaining portion of thefirst of the strip and adjacent casing sheet; and the backwardly-foldedpart of the strip is joined to the adjacent casing sheet along afastening line which extends generally along the side-edge of the stripand is curved in accordance with a desired outer contour of theside-flap of the article.
 5. The article according to claim 4, whereinthe strips forming the side-flaps extend over said second casing sheetand with their backwardly folded parts joined thereto.
 6. The articleaccording to claim 4 wherein each strip has straight, parallelside-edges when the article is extended longitudinally.
 7. The articleaccording to claim 4, wherein the side-edges of said second parts of thestrips are provided with elastic elements therealong.
 8. The articleaccording to claim 7, wherein the elastic elements include elastic bandsmounted adjacent said side-edges on at least one of the two surfaces ofthe strip.
 9. The article according to claim 3, wherein said strips arefastened to said outer casing sheet along a straight fastening line. 10.The article according to claim 9, wherein the strips are comprised ofdeformable material.
 11. The article according to claim 9, wherein thestrips are comprised of elastic material.
 12. A method of manufacturingan absorbent article, comprising:enclosing an absorbent material betweena moving web of liquid-permeable sheet material to form an inner casingsheet, and a moving web of liquid-impermeable sheet material to form anouter casing sheet; thereafter mutually joining said webs to form anabsorbent-unit web; forming two moving side-flap webs from sheetmaterial; joining the side-flap webs to the absorbent unit web; andcutting the thus formed combination of moving, mutually joined side-flapand absorbent unit webs transversely, such as to form separate absorbentarticles; arranging a first part of a width of each of said side-flapwebs adjacent a longitudinally extending side-edge of the absorbent unitweb over a portion of the absorbent material and joining said first webpart to the absorbent unit within this portion; and arranging aremaining, second part of the width of the side-flap web laterallyoutside the absorbent-unit web such as to form side-flaps.
 13. Themethod according to claim 12, further comprising folding said first partof the width of each side-flap web double along a fold line;joining thebackwardly folded part of said first web part to the absorbent unit webalong a curved fastening line extending generally in a longitudinaldirection of the web; and arranging that part of said second web partwhich is not folded back on that side of said backwardly folded partwhich lies remote from the absorbent unit web such that said part willextend from the fold line towards the side-edge of the absorbent unitweb and there merge with said second part of the width of the side-flapweb.
 14. The method according to claim 12, further comprising mountingelongated elastic elements along the side-edges of said secondwidth-parts of the side-flap webs and thereafter joining the firstwidth-parts of the side-flap webs with the absorbent-unit web.
 15. Anabsorbent article having an elongated absorbent unit, comprising:aliquid-permeable first, inner casing sheet which forms a part of a sideof the article which lies proximal to the wearer in a worn state of thearticle; a liquid-permeable second, outer casing sheet; and an elongatedabsorbent body enclosed between said first and second casing sheets; theabsorbent unit having two opposing long sides; the absorbent articlefurther having along each of said long sides a side-flap which is madeof a strip of sheet material whose length is greater than its width, andwhich is separate from but joined to one of said casing sheets; each ofsaid strips includes a first part that is folded backwardly along a foldline and arranged between the absorbent unit and a second part of thestrip, the fold line being substantially parallel to a longitudinaldirection of the absorbent unit; each of said strips being fastened tosaid absorbent unit by means of a curved fastening line that fastenssaid first part to the absorbent unit, wherein the fastening line isclosest to the fold line at a center of said absorbent unit and extendsaway from the absorbent unit at ends of the absorbent unit.